Is this the right way to create / destroy string in loop? - objective-c

Question

Just curious if this is the way to do this, just want to make sure its not leaking, although I would think I am only modifying the string contents.
NSMutableString *newPath = [[NSMutableString alloc] init];
for(fileName in [manager enumeratorAtPath:rootPath]){
if ([[fileName pathExtension] isEqual:#"exr"]) {
[fileArray addObject:fileName];
// THIS BIT
[newPath setString:rootPath];
[newPath appendString:#"/"];
[newPath appendString:fileName];
// HERE
attrDir = [manager attributesOfItemAtPath:newPath error:&myError];
fileSize = [attrDir objectForKey: #"NSFileSize"];
NSLog(#"File: /%# Size: %#", fileName, fileSize);
}
}
[newPath release];
gary

Answer 1

This looks fine leak-wise. If you're running Xcode 3.2 you can Build->Build & Analyzer to get Clang to check this sort of thing.
Remember you only have to release things you alloc, new, copy or retain.
Consider using stringByAppendingPathComponent, rather than hardcoding the #"/" path separator. NSString has a number of methods like this specifically for working with paths.
NSString* fullPath = [rootPath stringByAppendingPathComponent:fileName];

Answer 2

There's nothing wrong with it, although it could be better to use initWithFormat and release:
NSString *newPath = [[NSString alloc] initWithFormat:#"%#/%#",rootPath,fileName];
// do your thing
[newPath release];

Answer 3

There is absolutely nothing wrong with your code, it is correct memory management.
But it can be done with even less code and memory management needed:
for(fileName in [manager enumeratorAtPath:rootPath]){
if ([[fileName pathExtension] isEqualToString:#"exr"]) {
[fileArray addObject:fileName];
NSString* newPath = [rootPath stringByAppendingPathComponent:fileName];
attrDir = [manager attributesOfItemAtPath:newPath error:&myError];
fileSize = [attrDir objectForKey: #"NSFileSize"];
NSLog(#"File: /%# Size: %#", fileName, fileSize);
}
}